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On Android, SurfaceTextures provide a transform that should be applied to texture coordinates when sampling from the texture. Usually this is simply a y-flip, but sometimes it includes a scale and slight translation, eg when the video frame is contained within a larger texture. Previously we ignored this transform but performed a y-flip, meaning we rendered correctly most of the time, but not all of the time. Our first attempt to fix this was in bug 1731980. When rendering as a compositor surface with RenderCompositorOGLSWGL, we supplied the transform to CompositorOGL's shaders, which correctly fixed the bug for this rendering path. However, the attempted fix for hardware webrender in fact made things worse. As UV coordinates are supplied to webrender unnormalized, then the shaders normalize them by dividing by the actual texture size, this effectively handled the scale component of the transform. (Though not quite scaling by the correct amount, and ignoring the translation component, sometimes resulting in a pixel-wide green seam being visible at the video's edges.) When we additionally applied the transformation to the coordinates, it resulted in the scale being applied twice, and the video being rendered too far zoomed in. To make matters worse, when we received subsequent bug reports of incorrect rendering on various devices we mistakenly assumed that the devices must be buggy, rather than our code being incorrect. We therefore reverted to ignoring the transform on these devices, thereby breaking the software webrender path again. Additionally, on devices without GL_OES_EGL_image_external_essl3 support, we must sample from the SurfaceTexture using an ESSL1 shader. This means we do not have access to the correct texture size, meaning we cannot correctly normalize the UV coordinates. This results in the video being rendered too far zoomed out. And in the non-compositor-surface software webrender path, we were accidentally downscaling the texture when reading back into a CPU buffer, resulting in the video being rendered at the correct zoom, but being very blurry. This patch aims to handle the transform correctly, in all rendering paths, hopefully once and for all. For hardware webrender, we now supply the texture coordinates to webrender already normalized, using the functionality added in the previous patch. This avoids the shaders scaling the coordinates again, or using an incorrect texture size to do so. For RenderCompositorOGLSWGL, we continue to apply the transform using CompositorOGL's shaders. In the non-compositor-surface software webrender path, we make GLReadPixelsHelper apply the transform when reading from the SurfaceTexture in to the CPU buffer. Again using functionality added earlier in this patch series. This avoids downscaling the image. We can then provide the default untransformed and unnormalized UVs to webrender. As a result we can now remove the virtual function RenderTextureHost::GetUvCoords(), added in bug 1731980, as it no longer serves any purpose: we no longer want to share the implementation between RenderAndroidSurfaceTextureHost::Lock and RenderTextureHostSWGL::LockSWGL. Finally, we remove all transform overrides on the devices we mistakenly assumed were buggy. Differential Revision: https://phabricator.services.mozilla.com/D220582 |
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|---|---|---|
| .. | ||
| src | ||
| Cargo.toml | ||
| cbindgen.toml | ||
| DCLayerTree.cpp | ||
| DCLayerTree.h | ||
| Moz2DImageRenderer.cpp | ||
| moz.build | ||
| README.webrender | ||
| RenderAndroidHardwareBufferTextureHost.cpp | ||
| RenderAndroidHardwareBufferTextureHost.h | ||
| RenderAndroidSurfaceTextureHost.cpp | ||
| RenderAndroidSurfaceTextureHost.h | ||
| RenderBufferTextureHost.cpp | ||
| RenderBufferTextureHost.h | ||
| RenderCompositor.cpp | ||
| RenderCompositor.h | ||
| RenderCompositorANGLE.cpp | ||
| RenderCompositorANGLE.h | ||
| RenderCompositorD3D11SWGL.cpp | ||
| RenderCompositorD3D11SWGL.h | ||
| RenderCompositorEGL.cpp | ||
| RenderCompositorEGL.h | ||
| RenderCompositorLayersSWGL.cpp | ||
| RenderCompositorLayersSWGL.h | ||
| RenderCompositorNative.cpp | ||
| RenderCompositorNative.h | ||
| RenderCompositorOGL.cpp | ||
| RenderCompositorOGL.h | ||
| RenderCompositorOGLSWGL.cpp | ||
| RenderCompositorOGLSWGL.h | ||
| RenderCompositorRecordedFrame.h | ||
| RenderCompositorSWGL.cpp | ||
| RenderCompositorSWGL.h | ||
| RenderD3D11TextureHost.cpp | ||
| RenderD3D11TextureHost.h | ||
| RenderDcompSurfaceTextureHost.cpp | ||
| RenderDcompSurfaceTextureHost.h | ||
| RenderDMABUFTextureHost.cpp | ||
| RenderDMABUFTextureHost.h | ||
| RenderEGLImageTextureHost.cpp | ||
| RenderEGLImageTextureHost.h | ||
| RendererOGL.cpp | ||
| RendererOGL.h | ||
| RendererScreenshotGrabber.cpp | ||
| RendererScreenshotGrabber.h | ||
| RenderExternalTextureHost.cpp | ||
| RenderExternalTextureHost.h | ||
| RenderMacIOSurfaceTextureHost.cpp | ||
| RenderMacIOSurfaceTextureHost.h | ||
| RenderSharedSurfaceTextureHost.cpp | ||
| RenderSharedSurfaceTextureHost.h | ||
| RenderTextureHost.cpp | ||
| RenderTextureHost.h | ||
| RenderTextureHostSWGL.cpp | ||
| RenderTextureHostSWGL.h | ||
| RenderTextureHostWrapper.cpp | ||
| RenderTextureHostWrapper.h | ||
| RenderThread.cpp | ||
| RenderThread.h | ||
| rustfmt.toml | ||
| webrender_ffi.h | ||
| WebRenderAPI.cpp | ||
| WebRenderAPI.h | ||
| WebRenderTypes.cpp | ||
| WebRenderTypes.h | ||
To build and run WebRender in Gecko:
1. Install Rust if you don't have it already
If you are doing gecko builds already, you should already have Rust as it is a build requirement.
If not, you can install it using |mach bootstrap| (recommended) or from https://www.rust-lang.org/
Note: If installing manually, use the stable 64-bit release - on Windows make sure to use the MSVC ABI installer.
Ensure that rustc and cargo are in your $PATH (adding $HOME/.cargo/bin/ should be sufficient)
2. Build using |mach build|.
You don't need anything special in your mozconfig for local builds; webrender will be built by default.
3. Run with |MOZ_WEBRENDER=1| in your environment. e.g. |MOZ_WEBRENDER=1 ./mach run|.
Alternatively, you can set the gfx.webrender.all pref to true (browser restart required).
Note that on Linux, acceleration is disabled by default and it needs to be enabled for WebRender to work.
On Linux you can enable acceleration by putting |MOZ_ACCELERATED=1| in your environment, or setting layers.acceleration.force-enabled to true in about:config.
4. Verify WebRender is enabled. You can do this by going to about:support and checking the "Compositing" line in the Graphics section. It should say "WebRender".
There should also be a WebRender section under "Decision Log" in about:support, which will provide some more detail on what caused it to be enabled/disabled.
When making changes:
- Make the changes you want.
- Run |mach build| or |mach build binaries| as desired.
For a debug webrender build:
Use a debug mozconfig (ac_add_options --enable-debug)
You can also use an opt build but make webrender less optimized by putting opt-level=0 in the [profile.release] section of your toolkit/library/rust/Cargo.toml file
See also https://groups.google.com/forum/#!topic/mozilla.dev.servo/MbeMcqqO1fs